How much does the cathedral weigh?

I believe this question might have been inspired by the movie “Up”.When I was a newly-qualified tower guide I tried to learn the core facts and figures, and fortunately someone has nailed them to the model of the cathedral.

So if we add up the Chilmark, Purbeck, Lead, Timber, and an allowance of 75 tonnes for the stained glass plus another 50 tonnes or so of random artefacts (stalls, pulpits, altars etc) we get around 80,000 tonnes or 80 million kgs.

One litre of helium can lift about 1g (making a small allowance for the weight of the balloon itself) so to lift the cathedral you would need 80 billion litres of helium, or a balloon approximately 530m across.

(image produced by ME with no help from any AI agents, as you may be able to guess)

PS To my intense disappointment Mr Wikipedia tells me that the world’s entire helium reserves are less than half of this.  Also there is now a proposal to set up an International Helium Agency to stop people like me squandering helium on “wasteful usage” in balloons.